Dental and surgical hammer



-w. A. ARNESEN Erm.

DENTAL AND-SURGICAL HAMMER Filed Aug. 19, 1944 March 2, 194s'.

5%./ A@ LIM III'. Ir

INVENToRs W.. RNESEN BJ'IERTWECK 5W.DoTY .,Alf". ATTORNEY Patented Mar. 2, 1948 Flushing, and Spencer W. Doty, BaIdwin, N; Y., assignors, by direct and mesne assignments, to National Electric Instrument Company, Inc.; Elmhurst, Long Island, N. Y;,r a corporation of New York Application August 19, 1944, serial ne. 550,2?16

Claims. (o1. 12s-30's) This invention relates to improvements in den- Y ment over the instrument shown and described in Reiter, Patent No. 1,837,067, issued December 15, 19311-, for Automatic surgical mallet.

object of the invention is to provide an instrument of the foregoing.' type in which a piston, spring-actuated for imparting a sharp bloW- to a cutting instrument, has associated therewith im;- proved means for sol moving the piston as to compress the7 spring and for releasing the spring to exert its pent-up pressure at al predetermined time'.

Another object of the invention is to provide piston-operating means composed o'fa pin movable radially of the piston and having its upper surface tapered or cammed to engage a part of anI enclosing cylinder under the impetus of a moving device whereby such engagement of the cam surface releases the pin froml the' enga-ging device, simultaneously releasing the piston for movement under theimpetus'of an internal spring.

Another object of the invention is to provide in .an instrument as aboveA described special impact surfaces on thevv ends of parts thereof which are brought into percussive contact.- A Y A further lobject of the invention is to provide, in addition to the radially movable pin before de scribed, ae second radially movable pin cooperat ing with a formation in a wallA of the cylinder for limiting movement'of the piston carrying such pins;

A still further object of the invention is to provide simplied meanswherebyparts of the instrument can be held in assembly. y i

In` carrying out the foregoingl and other objectsof the invention,- use is made of a cylinder member within which is -slideably mounted a piston. One end of the cylinder is closed by a c ap member which retains a springin; position betweenA one endof theV piston and the cap. The other end ofV the cylinder is closed by a housing for al chuck carrying rod, such chuck carrying rod being movable relative to the housing. The outer end o f this rod is provided with a chuck for holding a chisel,- bit,v or other type of cutting device to be used with this instrument. Surrounding. the cylinder is an actuating member composedY in part of a sleeve towhich is loosely attached a member having. wings for engagement with the fingers of an operator and having a screw member passing through the wall of the sleeve with a part of the end of the screw rextending into a slot in the cylinder: The cylinder is provided with spa-ced radial bores which are normally aligned substantially with the slot in the cylinder. In each oi thesel radial bores is mount"- edI a spring compressed by a pin somewhat of the; order of a lock tumbler pin. The outer `endof one pin is of substantially cylindrical forniwithY the end rounded?, the,A cylindrical forinbeingV of a' diameter to fit closelyin the slot inI the cylinder with the" shoulder surroundingthis cylindrical' part engaging the inner wallY of the Acylinderuon: each side of the Slot.' The other pin isV 0f similar diameter in' its major portion but has diametricaily opposite flats' of such size as to provide anV intermediate portion fitting clc, selybetw*ee,nv the walls of the slot, and thev end; of1 this portion is cammedv tov slope inwardly f-romthe chuck end o'j the instrument toward'y the opposite endthereof, The actuating screw carried by the s leevebefore mentioned; engages the' high end of this cammed surface and is positioned betweenthetwo pins.- The' result of such engagement and o ftlive"con: struction is that movement of the actuating member away from the chuckcauses rnoveirient s in taneo'usly of the pistonin the sainen direwo When thev cammed surface contacts one of the slot in the cylinder,l continued movement forces the pin carryingthis surface inwardly og the piston until the high part of the surface is depressed suicientlyvtodclearut'heend of the actuating screwat whichtimethe .piston is released to Inovethe opposite direction under the impetusI ofthe spring interposed between the upper end of the piston and -the cap mentioned, and to impart apercussive blow tov the chuck carrying rod. Other features, objects and-advantagesorthe inventionr will' become apparent byhreferencemto the following detailed description of 4the accompanying drawings illustrating' the same, whore--r ev-Y (l--h- .n Fig. l is a side el eva tion p section of an instrument embodyi and in position immediately priojrt releasof tlie" piston aiording'apercussive'blow; Fig. 2 is an enlarged vertical seotion'triiougnan instrument em'bdying'th'e i'nventio'ri; suts't'anuaiiy the Fig. 3 is a section taken line 3-3fof Fig. 2; and

rtg. 4 is a fragmetaryview snovviiigtneiiiai: ner in which the pins previou'slymentioned col operate with theslot in the' cy1inder`vall. 'M

Referring now tothe2 drawings, andl pa'rticular-E ly to Fig. 2, lil indicates generally a cylinder made of some suitable material such as brass or any other desired metal, preferably of a type that may be plated to withstand the effects of sterilization. The upper end of this cylinder IIl is externally threaded as at Il, while the lower end thereof is internally threaded as at I2. Intermediate the ends of the cylinder the wall thereof is provided with a slot I4, shown both in Figs. 2 and 3, the latter View indicating clearly the width and relative length of the slot. Slideably mounted within limits within the cylinder I2 is a piston I5, preferably made of the same metal as the cylinder Ill. The upper end of piston I has a neck portion l5, while the lower end thereof is hollowed out to receive a hammer element I1 press-tted into the end of the piston. This hammer element il is preferably made of hardened stainless steel or any other material suitable for imparting and absorbing percussive shocks.

Intermediate the ends of the cylinder I5 are provided two bores 2D and 2I extending radially aconsiderable distance through the piston. Positioned in the bottom of the bore 2B is a small spring 22 held in place by a pin 24, the outer end of which has a cylindrical neck 25, the end of which is rounded. The other bore 2| likewise has a spring 25 therein held captive by a pin 2l, the outer end of which is provided with opposite flats 28, while the end thereof is provided with a flat cammed surface 29 extending inwardly of the device from bottom to top, as viewed in Fig. 2. The neck part 25 has a diameter of such size as to fit closely but slideably within the lslot I4, while the two flats 2B are so spaced as likewise to rit closely but slideably in the same slot. The respective shoulders on the pins 24 and 2l formed by the projection of the neck 25 and the flats 28 are of such conguration as to engage the inner surface of the cylinder I2 on each side of the slot I4, as shown in both Figs. 2 and 3.

.Threaded into the outer end of the cylinder Ill is a housing 3i] for a chuck carrying rod 3l. The housing 3l] has a portion thereof externally threaded to engage the internal threads I2; has a hollow bore for the passage of the rod 3l with the upper end of the bore enlarged to receive a coiled spring 32 surrounding rod 3l and held compressed by a through pin 34, the ends of which are free to move in diametrically opposite longitudinally extending slots in the upper part of the housing 3Q. Thearedly secured to the upper end of the rod 3l is an anvil member 35 of diameter larger than the hammer member Il but preferably made or" the same material as the hammer member I'I. The anvil member 35 is of sufcient diameter to overlie the upper end of the housing 39.

The lower end of the rod 3| is hollowed out with its extremities split to form chuck lingers which can be constricted by a rotatable member 4t threaded onto the end of the rod and having a suitable formation to constriot the chuck lingers. This chuck is adapted to hold a chisel, gouge or other instrument, as indicated at 4 I, against withdrawal or against relative rotation. The rod 3I is provided intermediate its ends with an external annular shoulder 42, the purpose of which will be explained later. A set screw 43 threaded through the cylinder and engaging the housing Silprevents movement of the housing and also rod SI, due to through pin 34,

Surrounding a part of cylinder I0 is a sleeve member 45 which has an enlargement 46, against the lower edge of which is retained a freely rotatable double wing-like member 41, the wings of which are shaped to be engaged by ngers of an operator. This member 4l is retained in place by its engagement with the enlargement 46 and also by a spring ring 48 tting in a shallow groove cut in the outer surface of sleeve 45. The enlargement 46 has a through aperture internally threaded for the reception of a screw 50, the end of which is provided with a smooth neck of diameter to t in the slot I4 between the neck 25 and the high end of the tapered or cammed surface 29.

Secured to the upper end of the vcylinder IIl is a cap member which has a portion of internal diameter to be internally threaded into engagement with threads Il, and another portion of larger internal diameter to encompass a coiled spring 6B surrounding the cylinder it and held captive between the upper end of the sleeve 45 and a spring split ring SI seated in a shallow groove in the wall of cylinder Ill. This latter part of the cap extends down far enough to normally overlie the upper end of the sleeve 45 and is of such dimensions as to permit the sleeve to be retracted into the cap against tension of spring 6D. Another spring 52 is entrapped in the space between the top of piston I5 and the top of cap 55, the neck I6 of the piston fitting within the spring. The top of cap 55 has a through aperture to loosely receive a stud 64 on the underside of a hand fitting member 65, such stud being loosely retained in place by a spring ring 66 fitting in a shallow groove in the stud.

When the device is assembled, the piston I5 can be'interposed into the cylinder Il) at the threaded end thereof and pressed upwardly. The cam surface 29, upon engaging the lower edge of the wall of the cylinder, will be moved inwardly of the piston, permitting the piston to slide upwardly in the cylinder, while the pin 24 can be depressed until the neck 25 will engage under the wall of the cylinder, at which time the piston can be moved upwardly with the parts 29 and 25 in substantial alignment with slot I4 until this slot is reached, at which time the ends of the respective pins will protrude into the slot and thereby restrain the piston from undesired movement in either direction.

The operation and use of the instrument is substantially as follows. With all parts in the relative position shown in Fig. 2, and particularly with a cutting tool 4I, such as a chisel, gouge or the like, engaged in the chuck on the end of rod 3|, the instrument can be manipulated to apply repeated percussive blows to the upper end of rod 3I so that such blows .can be transmitted to the cutting end of the tool 4I. To accomplish such a percussive blow, the sleeve 45 is moved upwardly by a clenching of the operators hand, the instrument being held lwith the member 45 against the heel of the hand and between the thumb and forenger thereof and' with two fingers engaged under the wings of the part 41. Movement of sleeve 45 upwardly carries piston I5 along with it, since the neck of screw 5t is in register with the groove I4 and lies between the neck 25 and the high edge of the cam surface 29. When the lower edge of cam surface 2S contacts the upper end wall of slot I4, continued` movement of sleeve 45 upwardly causes the pin 21 to be moved inwardly radially of the piston, and such movement continues until the piston has been moved upwardly a distance suiTicient to cause the pin 21 to be depressed an amount necessary to clear the inner end ofthe neck ofthe screw 50, atwhich time the higher edge of surface 29 is free to pass under the screw 55. At this time the spring 62 having been compressed by the upward movement of the piston forces the piston downwardly to cause the hammer member I1 to strike the anvil member 35. During the initial stages of upwardmovement of the piston the rod 3I follows such movement until the annular shoulder 42 engages the lower end of a housing member 30. Such following action is due to the spring 32 expanding and forcing the pin 3a upwardly, the ends ofthe pin riding in the slot in the housing 30. As soon as the collar 42 contacts the lower end of housing 30, further upward movement of rod 3l is arrested, and such arrest occurs well before the end of the upward movement of the piston. As will be seen by reference to Fig. 2, a gap is created between the hammer I1 and the anvil 35, which gap is widenedr until the pin 21 is released from duress by the screw Eil. When this release occurs, as before mentioned, the piston I is immediately forced downwardly by expansion of spring 62 with the result that hammer II strikes anvil 35 a sharp blow, causing depression of hammer 35 and consequent downward movement of rod 3|. This downward movement continues until the lower edge or surface of anvil 35 rests against the upper edge of. the housing 35 within the cylinder I0.

Upward movement of sleeve 4E before described compresses the spring 63 surrounding the cylinder Ii) with the result that, when finger pressure is released from thewlngs of member 41, spring Gil expands, carrying the sleeve downwardly and eventually causing the. end of the neck of screw 5i!v to engage the cam surface 29 and ride thereover, momentarily depressing pin 21, the downward movement of the sleeve being continued until the neck of screw 5e contacts the neck 25 of pin 24. The parts are then in their normal position ready for a repeated operation of theV instrument to cause the transmission of the force of a percussive blow from the hammer to the cutting edge of the tool 4I.

The pin 24 with its neck part 25 fitting closely but slideably in the groove I4 prevents any possible rotation of piston I5 in the cylinder at such time as the pin 21 might be depressed to an extent suicient to permit the piston to rotate were this neck 25 omitted. Also, the neck 25 serves as a stop limiting downward movement of the screw 50 and thereby determining the normal position of sleeve 45. This pin 24 and neck 25 also have' the function of preventing the piston from being can be readily replaced with Ia 'minimum of vexpense and labor attendant thereto. It is to be understood that modifications beyond the illustrated embodiments can be made without depart--v ing from the spirit of the invention, and accordingly such limitations as to be imposed thereupon are only those set forth in the following claims.

What is claimed is:

l. An instrument of the` typey described comprising a cylinder, a piston slideable in said cylf inder, a tool carrying rod slideably secured in one end of said cylinder, means for limiting sliding movementl of said rod, said cylinder having a longitudinally extending slot in the wall thereof intermediate the ends of theY cylinder, an outwardly biased pin movable radially in said piston and having a portion fitting in and extending partially through said slot, a spring captive at one end of said piston, and a member extending partially through said slot and engaging said portion to move it and said piston in a direction to compress said spring, lsaid tool carrying rod being normally held by said piston at the outer end of its limit of movement and being biased to follow said piston to the inner end of its limit of movement as the piston compresses said spring, said portion being, disengaged from said member byI progressive engagement with the end wall 0f said slot whereby said pistonv is freed to impart a blow to said rod and drive it from one endl of its limit of movement to the other end thereof.

2. An instrument of the type described comprising a cylinder, a piston slideable in said cylind'er, a tool carrying rodv slideably secured in one end' of said cylinder, means for limiting sliding movement of said rod.. said' cylinder having a longitudinally extending sl'ot in the-'wall thereof intermediate the ends of the cylinder, an outwardly biased pinA movable radially in said piston and having a portion fittingA in and extending partially through said slot, said pin having shoulders on each side of said portion engaging and' slid"- forced downwardly in the cylinder an undesired amount should the housing 30 be withdrawn for inspection or repairs or for any other purpose. As before mentioned, the various parts of the device, with the exception of the portions I 'I and 35, can be made of any suitable material, such as brass, which can be plated to withstand the action of sterilizing nuids at high temperature, while the parts II and 35 are preferably made of such hardened material as to remain undamaged after repeated use of the instrument with attendant percussive blows of one on the other. The use of ring split members 48, 6I and 66 facilitates assembly or dismantling of the instrument and reduces the cost of machined parts materially.

From the foregoing it will be seen that the present invention provides an improved dental or surgical hammer of the utmost simplicity but of a ruggedness suitable for repeated use without material wear. The parts subjectV to most wear able along the inner wall of said cylinder adjacent the edges ofsaid slot, said shoulders limiting outward movement of said pin, the outer end of said portion having a cam surface, and having parallel side Walls cooperating with the walls of said slot to prevent rotation of the pin'relative to the cylinder, spring captive at one end of said piston, and a member extending partially through said seat and engaging said portion to move it andsaid piston in a direction to compress said spring, said tool carrying rod being normally held by said piston at the outer end of its limit of movement and being biased to following said piston to the inner end of its limit of movement as the piston compresses said spring, said portion being disengaged from said member by cam action of said cam surface against the end wall of said slot whereby said piston is freed to impart a blow to said rod and drive it from one end of its limit of movement to the other end thereof.

3. An instrument of the type described comprising a cylinder, a piston slideable in said cylinder, a tool carrying rod slideably secured in one end of said cylinder, means for limiting sliding movement of said rod, said cylinder having a longitudinally extending slot in the wall thereof intermediate the ends of the cylinder, an outwardly biased pin movable radially in said piston and having a portion fitting in said slot, the outer end of said portion having a cam surface and having parallel side walls cooperating with the walls of said slot to prevent rotation of the pin relative to the cylinder, a second outwardly biased pin movable radially in said piston and having a neck tting in and extending partially through said slot to prevent rotation of said piston relative to said cylinder, e, spring captive at one end of said piston, and a member tting between said portion and said neck, said member engaging said portion to move it and said piston in a direction to compress said spring, said tool carrying rod being normally held by said piston at the outer end of its limit of movement and being biased to follow said piston to the inner end of its limit of movement as the piston compresses said spring, said portion being disengaged from said member by cam action of said cam surface against thev end wall of said slot whereby said piston is freed to impart a blow to said rod anddrive it from one end of its limit of movement to the other end thereof.

4. An instrument of the type described comprising a cylinder, a piston slideable in said cylinder, a tool carrying rod slideably secured in one end of said cylinder, means for limiting sliding' movement of said rod, said cylinder having a longitudinally extending slot in the wall thereof intermediate the ends of the cylinder, a pin movable radially in said piston and having a portion fitting in and extending partially through said slot, the outer end of said portion having a cam surface and having parallel side walls cooperating with the walls of said slot to prevent rotation of the pin relative to the cylinder, a spring captive at one end of said piston, and a member extending partially through said slot and engaging said portion to move it and said piston in a direction to compress said spring, said tool carrying rod being normally held by said piston at the outer end of its limit of movement and being biased to follow said piston to the inner end of its limit of movement as the piston compresses said spring, said portion being disengaged from said member by cam action of said cam surface against the end wall of said slot whereby said piston is freed to impart a blow to said rod and drive it from one end of its limit of movement to the other end thereof, said piston and said rod having hardened inserts in the contacting ends thereof.

5. An instrument of the type described comprising a cylinder, a piston slideable in said cylinder, a tool carrying rod slideably secured in one end of said cylinder, means for limiting sliding movement of said rod, said cylinder having a longitudinally extending slot in the wall thereof intermediate the ends of the cylinder, a pin movable radially in said piston and having a portion tting in and extending partially through said slot, a spring, a cap attached to said cylinder and holding said spring captive at one end of said piston, a sleeve carrying a member extending partially through said slot and engaging said portion to move it and said piston in a directio to compress said spring, said tool carrying r being normally held by said piston at the out r end of its limit of movement and being biase to follow said piston to the inner end of its limit of movement as the piston compresses said spring, said portion being disengaged from said member by progressive engagement with the end Wall of said slot whereby said piston is freed to impart a blow to said rod and drive it from one end of its limit of movement to the other end thereof, and a second spring surrounding said cylinder for restoring said Sleeve to normal position, said cap having a skirt portion covering said second spring.

The following references are of record in the file of this patent:

Y UNITED STATES PATENTS Number Name Date 863,909 Evans Aug. 20, 1907 1,837,067 Reiter Dec. 15, 1931 

